In a field of an operation machine such as an excavator, there is a case where a plurality of cameras is provided on a rear side or a side of its vehicle body in addition to a mirror in such a manner that an operator (driver) can visually recognize an obstacle near the vehicle body. Then, an image imaged by a camera is displayed, as a single camera image, on its monitor in an operating room of the operation machine.
Also, there is one which generates a bird's eye image by converting an image of each camera into a top view and by composing images of cameras and displays the bird's eye image on the monitor in such a manner that 360° around a vehicle body can be observed. Also, there is one which displays a single camera image imaged by a camera selected by an operator, on the monitor in addition to the bird's eye image (see Patent Literature 1).
Moreover, in a large operation machine such as a large excavator, an operating room is provided at a high position from the ground. Thus, a boarding ladder is provided to allow an operator to access the operating room (see Patent Literature 2). Lifting/lowering control is performed on the lifting ladder when the operator gets in and out of the large operation machine.